Method and apparatus for performing rank overriding in long term evolution networks

Abstract

Apparatus and method of generating a long term evolution (LTE) codebook and performing rank overriding are disclosed. Reordering rules are presented, whereby a second column vector of each rank-4 precoding matrix will not appear in column vectors of a rank-3 precoding matrix, and the first column vector of each rank-4 precodingmatrix is identical to the first column vector of the corresponding rank-3 precodingmatrix. Furthermore, precoder hopping between two precoding matrices corresponding to a particular precoding matrix index (PMI) is implemented, whereby a first one of the two precoding matrices comprises a first subset of column vectors of an original precoding matrix that corresponds to the particular PMI, and a second one of the two precoding matrices comprises a second subset of column vectors of the original precoding matrix. The precoder hopping is performed in time and/or frequency domain.

1 . A wireless communication method of generating a long term evolution (LTE) codebook having a rank-1 column, a rank-2 column, a rank-3 column and a rank-4 column, each column including a plurality of precoding matrices, each precoding matrix corresponding to a respective precoding matrix index (PMI), the method comprising:
 assigning a first column vector to each of the precoding matrices in the rank-1 column;   assigning a first column vector and a second column vector to each of the precoding matrices in the rank-2 column;   assigning a first column vector, a second column vector and a third column vector to each of the precoding matrices in the rank-3 column; and   assigning a first column vector, a second column vector, a third column vector and a fourth column vector to each of the precoding matrices in the rank-4 column, wherein the second column vector of any precoding matrix in the rank-4 column that corresponds to a particular PMI is not included in a precoding matrix in the rank-3 column that also corresponds to the particular PMI.   
   
   
       2 . The method of  claim 1  wherein the LTE codebook has sixteen different PMIs. 
   
   
       3 . A wireless communication method of generating a long term evolution (LTE) codebook having a rank-1 column, a rank-2 column, a rank-3 column and a rank-4 column, each column including a plurality of precoding matrices, each precoding matrix corresponding to a respective precoding matrix index (PMI), the method comprising:
 assigning a first column vector to each of the precoding matrices in the rank-1 column;   assigning a first column vector and a second column vector to each of the precoding matrices in the rank-2 column;   assigning a first column vector, a second column vector and a third column vector to each of the precoding matrices in the rank-3 column, wherein either the second or third column vector of each precoding matrix in the rank-3 column that corresponds to a particular PMI is the same as the second column vector in a precoding matrix in the rank-2 column that also corresponds to the particular PMI; and   assigning a first column vector, a second column vector, a third column vector and a fourth column vector to each of the precoding matrices in the rank-4 column, wherein the first column vector of each precoding matrix in the rank-4 column that corresponds to a particular PMI is the same as the first column vector in a precoding matrix in the rank-3 column that also corresponds to the particular PMI, and the last two column vectors of each precoding matrix in the rank-4 column that corresponds to a particular PMI are the same as the last two column vectors in the rank-3 column for the particular PMI.   
   
   
       4 . The method of  claim 3  wherein the LTE codebook has sixteen different PMIs. 
   
   
       5 . A wireless communication method of performing rank overriding using frequency domain precoder hopping in a long term evolution (LTE) codebook having a rank-1 column, a rank-2 column, a rank-3 column and a rank-4 column, each column including a plurality of precoding matrices having column vectors assigned thereto, each precoding matrix corresponding to a respective precoding matrix index (PMI), the method comprising:
 alternating between the use of two precoding matrices corresponding to a particular PMI, whereby a first one of the two precoding matrices comprises a first subset of column vectors of an original precoding matrix that corresponds to the particular PMI, and a second one of the two precoding matrices comprises a second subset of column vectors of the original precoding matrix,   
   
   
       6 . The method of  claim 5  wherein the alternating is implemented by precoder hopping that is performed in time domain. 
   
   
       7 . The method of  claim 6  wherein the first one of the two precoding matrices is applied on all subcarriers of odd orthogonal frequency division multiplexing (OFDM) symbols, and the second one of the two precoding matrices is applied on all subcarriers of even OFDM symbols. 
   
   
       8 . The method of  claim 5  wherein the alternating is precoder hopping that is performed in frequency domain. 
   
   
       9 . The method of  claim 5  wherein the alternating is precoder hopping that is performed in frequency and time domain. 
   
   
       10 . The method of  claim 9  wherein the first one of the two precoding matrices is applied on all odd subcarriers of odd orthogonal frequency division multiplexing (OFDM) symbols, and on all even subcarriers of even OFDM symbols, and the second one of the two precoding matrices is applied on all even subcarriers of odd OFDM symbols, and on all odd subcarriers of even OFDM symbols. 
   
   
       11 . A wireless transmit/receive unit (WTRU) configured to generate a long term evolution (LTE) codebook having a rank-1 column, a rank-2 column, a rank-3 column and a rank-4 column, each column including a plurality of precoding matrices, each precoding matrix corresponding to a respective precoding matrix index (PMI), the WTRU comprising:
 a multiple-input multiple-output (MIMO) antenna; and   a processor configured to:   assign a first column vector to each of the precoding matrices in the rank-1 column;   assign a first column vector and a second column vector to each of the precoding matrices in the rank-2 column;   assign a first column vector, a second column vector and a third column vector to each of the precoding matrices in the rank-3 column; and   assign a first column vector, a second column vector, a third column vector and a fourth column vector to each of the precoding matrices in the rank-4 column, wherein the second column vector of any precoding matrix in the rank-4 column that corresponds to a particular PMI is not included in a precoding matrix in the rank-3 column that also corresponds to the particular PMI.   
   
   
       12 . The WTRU of  claim 11  wherein the LTE codebook has sixteen different PMIs. 
   
   
       13 . A wireless transmit/receive unit (WTRU) configured to generate a long term evolution (LTE) codebook having a rank-1 column, a rank-2 column, a rank-3 column and a rank-4 column, each column including a plurality of precoding matrices, each precoding matrix corresponding to a respective precoding matrix index (PMI), the WTRU comprising:
 a multiple-input multiple-output (MIMO) antenna; and   a processor configured to:
 assign a first column vector to each of the precoding matrices in the rank-1 column; 
 assign a first column vector and a second column vector to each of the precoding matrices in the rank-2 column; 
 assign a first column vector, a second column vector and a third column vector to each of the precoding matrices in the rank-3 column, wherein either the second or third column vector of each precoding matrix in the rank-3 column that corresponds to a particular PMI is the same as the second column vector in a precoding matrix in the rank-2 column that also corresponds to the particular PMI; and 
 assign a first column vector, a second column vector, a third column vector and a fourth column vector to each of the precoding matrices in the rank-4 column, wherein the first column vector of each precoding matrix in the rank-4 column that corresponds to a particular PMI is the same as the first column vector in a precoding matrix in the rank-3 column that also corresponds to the particular PMI and the last two column vectors of each precoding matrix in the rank-4 column that corresponds to a particular PMI are the same as the last two column vectors in the rank-3 column for the particular PMI. 
   
   
   
       14 . The WTRU of  claim 13  wherein the LTE codebook has sixteen different PMIs. 
   
   
       15 . A wireless transmit/receive unit (WTRU) configured to perform rank overriding using frequency domain precoder hopping in a long term evolution (LTE) codebook having a rank-1 column, a rank-2 column, a rank-3 column and a rank-4 column, each column including a plurality of precoding matrices having column vectors assigned thereto, each precoding matrix corresponding to a respective precoding matrix index (PMI), the WTRU comprising:
 a multiple-input multiple-output (MIMO) antenna; and   a processor configured to alternate between the use of two precoding matrices corresponding to a particular PMI, whereby a first one of the two precoding matrices comprises a first subset of column vectors of an original precoding matrix that corresponds to the particular PMI, and a second one of the two precoding matrices comprises a second subset of column vectors of the original precoding matrix,   
   
   
       16 . The WTRU of  claim 15  wherein the alternating is implemented by precoder hopping that is performed in time domain. 
   
   
       17 . The WTRU of  claim 16  wherein the first one of the two precoding matrices is applied on all subcarriers of odd orthogonal frequency division multiplexing (OFDM) symbols, and the second one of the two precoding matrices is applied on all subcarriers of even OFDM symbols. 
   
   
       18 . The WTRU of  claim 15  wherein the alternating is precoder hopping that is performed in frequency domain. 
   
   
       19 . The WTRU of  claim 15  wherein the alternating is precoder hopping that is performed in frequency and time domain. 
   
   
       20 . The WTRU of  claim 19  wherein the first one of the two precoding matrices is applied on all odd subcarriers of odd orthogonal frequency division multiplexing (OFDM) symbols, and on all even subcarriers of even OFDM symbols, and the second one of the two precoding matrices is applied on all even subcarriers of odd OFDM symbols, and on all odd subcarriers of even OFDM symbols. 
   
   
       21 . A base station configured to generate a long term evolution (LTE) codebook having a rank-1 column, a rank-2 column, a rank-3 column and a rank-4 column, each column including a plurality of precoding matrices, each precoding matrix corresponding to a respective precoding matrix index (PMI), the base station comprising:
 a multiple-input multiple-output (MIMO) antenna; and   a processor configured to:   assign a first column vector to each of the precoding matrices in the rank-1 -column;   assign a first column vector and a second column vector to each of the precoding matrices in the rank-2 column;   assign a first column vector, a second column vector and a third column vector to each of the precoding matrices in the rank-3 column; and   assign a first column vector, a second column vector, a third column vector and a fourth column vector to each of the precoding matrices in the rank-4 column, wherein the second column vector of any precoding matrix in the rank-4 column that corresponds to a particular PMI is not included in a precoding matrix in the rank-3 column that also corresponds to the particular PMI.   
   
   
       22 . The base station of  claim 21  wherein the LTE codebook has sixteen different PMIs. 
   
   
       23 . A base station configured to generate a long term evolution (LTE) codebook having a rank-1 column, a rank-2 column, a rank-3 column and a rank-4 column, each column including a plurality of precoding matrices, each precoding matrix corresponding to a respective precoding matrix index (PMI), the base station comprising:
 a multiple-input multiple-output (MIMO) antenna; and   a processor configured to:
 assign a first column vector to each of the precoding matrices in the rank-1 column; 
 assign a first column vector and a second column vector to each of the precoding matrices in the rank-2 column; 
 assign a first column vector, a second column vector and a third column vector to each of the precoding matrices in the rank-3 column, wherein either the second or third column vector of each precoding matrix in the rank-3 column that corresponds to a particular PMI is the same as the second column vector in a precoding matrix in the rank-2 column that also corresponds to the particular PMI; and 
 assign a first column vector, a second column vector, a third column vector and a fourth column vector to each of the precoding matrices in the rank-4 column, wherein the first column vector of each precoding matrix in the rank-4 column that corresponds to a particular PMI is the same as the first column vector in a precoding matrix in the rank-3 column that also corresponds to the particular PMI and the last two column vectors of each precoding matrix in the rank-4 column that corresponds to a particular PMI are the same as the last two column vectors in the rank-3 column for the particular PMI. 
   
   
   
       24 . The base station of  claim 23  wherein the LTE codebook has sixteen different PMIs. 
   
   
       25 . A base station configured to perform rank overriding using frequency domain precoder hopping in a long term evolution (LTE) codebook having a rank-1 column, a rank-2 column, a rank-3 column and a rank-4 column, each column including a plurality of precoding matrices having column vectors assigned thereto, each precoding matrix corresponding to a respective precoding matrix index (PMI), the base station comprising:
 a multiple-input multiple-output (MIMO) antenna; and   a processor configured to alternate between the use of two precoding matrices corresponding to a particular PMI, whereby a first one of the two precoding matrices comprises a first subset of column vectors of an original precoding matrix that corresponds to the particular PMI, and a second one of the two precoding matrices comprises a second subset of column vectors of the original precoding matrix,   
   
   
       26 . The base station of  claim 25  wherein the alternating is implemented by precoder hopping that is performed in time domain. 
   
   
       27 . The base station of  claim 26  wherein the first one of the two precoding matrices is applied on all subcarriers of odd orthogonal frequency division multiplexing (OFDM) symbols, and the second one of the two precoding matrices is applied on all subcarriers of even OFDM symbols. 
   
   
       28 . The base station of  claim 25  wherein the alternating is precoder hopping that is performed in frequency domain. 
   
   
       29 . The base station of  claim 25  wherein the alternating is precoder hopping that is performed in frequency and time domain. 
   
   
       30 . The base station of  claim 29  wherein the first one of the two precoding matrices is applied on all odd subcarriers of odd orthogonal frequency division multiplexing (OFDM) symbols, and on all even subcarriers of even OFDM symbols, and the second one of the two precoding matrices is applied on all even subcarriers of odd OFDM symbols, and on all odd subcarriers of even OFDM symbols.